1. Field of the Invention
The present invention relates to a piezoelectric element including a lower electrode, a piezoelectric layer and an upper electrode. Specifically, the present invention relates to a liquid-jet head which ejects droplets from nozzle orifices, and a piezoelectric element used for a liquid-jet apparatus.
2. Description of the Prior Art
An inkjet recording head with the following configuration has been put into practical use. In accordance with the configuration, a part of pressure generating chambers communicating with nozzle orifices from which ink droplets are ejected is constructed with a vibration plate. The vibration plate is deformed by piezoelectric elements, and thus ink in each of the pressure generating chambers is pressurized. Accordingly, ink droplets are ejected from each of the nozzle orifices. An inkjet recording head which is constructed, for example, in the following manner is among such inkjet recording heads. An even layer made of a piezoelectric material is formed on the entire surface of the vibration plate by use of a film-forming technique. Then, this layer made of the piezoelectric material is cut into shapes corresponding to the pressure generating chambers by a lithography method. Thereby, the piezoelectric elements are formed respectively in the pressure generating chambers in order that the piezoelectric elements can be independent from one another.
A piezoelectric element including a piezoelectric layer with a withstand voltage, which is improved by means of suppressing a leakage current thereof, has been proposed as such a piezoelectric element used for such inkjet recording heads, the leakage current being suppressed by means of setting an amount of halogen material contained therein as a component of the piezoelectric layer. (See claims in pp. 11 of Japanese Patent Laid-open Official Gazette No. 2004-107181, for example)
However, according to Japanese Patent Laid-open Official Gazette No. 2004-107181, although the leakage current of the piezoelectric layer can be suppressed, an electric resistivity of the piezoelectric layer is not set. Accordingly, there has been a problem that the durability of the piezoelectric layer is deteriorated due to an increased leakage current if the electric resistivity is lower.
Note that, such problems are not limited to liquid-jet heads represented by inkjet recording heads. The problems are similarly present in other piezoelectric elements.